The invention relates to a web drying unit, for a paper making machine, for example.
As known, the drying section of a paper making machine is divided into several drying units. It is customary for at least one drive motor to be provided for each drying unit, which motor usually drives via gear wheels several drying cylinders over which the web can pass.
It is also known to provide a geared motor for each drying cylinder, or for some individual drying cylinders, or to drive only some individual guide rolls of a supporting belt for pressing the web against the drying cylinders. In the latter case those drying cylinders which are not connected by gearing to the drive are driven via the supporting belt.
Some disadvantages of the known drives include the following:
(a) The frames on the front side and the drive side of the unit are not identical; consequently, irregular ventilation conditions occur, which result in an effect on the profile of paper dryness in the cross-machine direction;
(b) The drive motor and associated universal-joint shaft are normally located in a region at body height and result in an obstruction to maintenance personnel along the drive side;
(c) Separate drives are required for cylinders and guide rolls, which is cost-intensive.